Fig. 5
NCTD inhibits proliferation of HT-29 cells, HDLECs and the co-culture system in vitro. a The dose–response curves of NCTD effect on HT-29 cells, HDLECs and the co-culture system with IC50 value 56.8 μg/ml for HT-29 cells, 6.8 μg/ml for HDLECs and 15.8 μg/ml for the co-culture system. Cell number was counted by the MTT method. b Histomorphologic of HT-29 cells, HDLECs and the co-culture system under an inverted optic microscope (magnification × 200) and a TEM (magnification × 8000): predominantly shuttle-shape cells, with abundant cytoplasm, clear nuclei, and abundant microvillus, clear organelles, larger nucleus cytoplast ratio, irregular nuclei and chromatin enrichment in control group; after treatment with 1/3 IC50 NCTD for 24 h, visible cell aggregation, float, nuclear shrinkage, chromosome condensation, microvillus decreasing, golgiosome atrophy, mitochondria swell, cytoplast vacuole, nuclear fragmentation, chromatin aggregation and typical apoptotic bodies, or even death. c The inhibitory effect of NCTD on expression of proliferating marker Ki-67 in HDLECs and the co-culture system in vitro. The positive expression, with brown-yellow dye, of Ki-67 protein product occurred in cell nucleoli. After treatment with 1/3 IC50 NCTD for 48 h, the positive index of Ki-67 expression in HDLECs (0.696 ± 0.0611 vs. 0.221 ± 0.042) or the co-culture system (0.964 ± 0.098 vs. 0.397 ± 0.068) was respectively decreased significantly as compared to control group (all P < 0.001), and the dye of cell nucleoli became light and shallow